Attenuated Mannheimia haemolytica Strains

ABSTRACT

The present invention provides attenuated  M. haemolitica  strains that elicit an immune response in animal against  M. haemolitica , compositions comprising said strains, methods of vaccination against  M. haemolitica , and kits for use with such methods and compositions. The invention further provides multi-valent vaccines, which provide protective immunity when administered in an effective amount to animals susceptible to “shipping fever” or bovine respiratory disease.

INCORPORATION BY REFERENCE

This application claims priority to U.S. provisional patent applicationSer. No. 61/723,979, filed on Nov. 8, 2012, and herein incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to attenuated bacterialvaccines, particularly those providing broad, safe, and effectiveprotection to production animals against infections/disease caused bygram-negative bacteria, including Mannheimia (Pasteurella) haemolytica.The invention further relates to methods of producing the attenuatedbacteria, and to PCR methods for differentiating among M. haemoliticaserotypes A1 and A6, in vivo.

The invention accordingly relates to immunogenic or vaccine compositionscomprising the bacteria of the invention; e.g., live attenuatedbacteria. The bacteria also could be inactivated in the compositions,but it may be advantageous that the bacteria are live attenuated M.haemolytica bacteria, either alone, or combined with other bacteria suchas Haemophilus Somnus and/or Pasteurella Multocida. The inventiontherefore further relates to methods for preparing and/or formulatingsuch compositions; e.g., culturing or growing or propagating thebacteria on or in suitable medium, harvesting the bacteria, optionallyinactivating the bacteria, and optionally admixing the bacteria with asuitable veterinarily or pharmaceutically acceptable carrier, excipient,diluent or vehicle and/or an adjuvant and/or stabilizer. Thus, theinvention also relates to the use of the bacteria in formulating suchcompositions.

BACKGROUND OF THE INVENTION

M. haemolytica is a gram negative bacterium normally found in the upperrespiratory tract of healthy cattle, sheep and wild sheep. M.haemolytica descends into the lungs when cattle experience stress suchas shipping, weaning, overcrowding, or viral infections and causesfibrinous and necrotizing bronchopneumonia, a chief component of thebovine respiratory disease complex (BRDC). Economic losses due to BRDCin North America is >$1 billion annually (Bowland and Shewen, 2000). M.haemolytica is the bacterium most commonly isolated from the lungs ofcattle affected with BRDC. M. haemolytica serotype A1 is responsible forapproximately 60% of shipping fever, whereas serotypes A6 and A2 accountfor 26% and 7% respectively (Al-Ghamdi et al., 2000; Purdy et al.,1997). Both M. haemolytica A1 and A6 account for >85% of BRDC casesinvolving bacterial pathogens.

The vaccines currently available in the market against M. haemolyticainfections are only moderately protective against shipping fever of beefcattle but generally ineffective against neonatal dairy calf pneumonia(Virtala et al., 1996; Rice et al., 2007). The major cause of severebacterial pneumonia in feedlot and neonatal dairy cattle is M.haemolytica serotype A1 followed by serotype A6 (Schreuer et al., 2000,Rice et al., 2007).

Experimental evaluation of all the commercial M. haemolytica A1 vaccinesused in feedlot showed only partial protection in 50% of the studies(Perino and Hunsaker, 1997). Furthermore, cross-protection against M.haemolytica serotypes (either A6 or A2) has been difficult to achieveusing conventional vaccine preparations (Purdy et al., 1993; Sabri etal., 2000). Therefore, an efficacious vaccine against M. haemolyticaserotypes A1 and A6 could significantly improve dairy/beef production.

Effective immunity against M. haemolytica is multifaceted. NeutralizingAntibodies against exotoxin leukotoxin A (LktA) and surface antigens arenecessary for protective immunity against M. haemolytica (Shewen andWilkie, 1988). Due to the complex genetic machinery involved incontrolling the expression of various M. haemolytica virulence factors,the specific surface antigens that are important in stimulating immunityhave not been clearly determined (Lawrence et al, 2010). However, M.haemolytica outer membrane proteins (OMPs) have been implicated instimulating immunity against surface antigens (Confer et al., 2003,Morton et al., 1995; Potter et al., 1999).

Intranasal immunization of cattle has been pursued for a while usingbovine herpesvirus-1 (BoHV-1), bovine respiratory syncytial virus (BRSV)and infectious bovine rhinotracheitis virus (IBR) (Ellis et al., 2007;Muylkens et al., 2007). Commercially available Pfizer's INFORCE 3 whenadministered intranasally claims to prevent BRSV and also aids in theprevention of respiratory disease caused by IBR and bovine parainfluenzavirus type 3 (PI3).

In an experimental study when a modified live leukotoxin deficient M.haemolytica mutant was administered intranasally in weaned beef feedlotcalves, it resulted in reduced nasopharyngeal colonization with wildtype M. haemolytica compared to non-vaccinated control calves (Frank etal., 2003). Although intranasal vaccination and leukotoxin deficient M.haemolytica are known, inventors are aware of no M. haemolytica vaccinessuccessfully combining these concepts.

SUMMARY OF THE INVENTION

An object of the present disclosure is to provide effective vaccinescomprising attenuated M. haemolytica serotypes A1 & A6. Relative to aparent M. haemolytica serotype A1 or A6 strain, the attenuated strainsmay have genomic modifications, including deletions, substitutions, andadditions, and whose presence (or absence) is associated with reducedvirulence. In an embodiment, a wildtype M. haemolytica (serotype A1D153) may be modified to contain a partial gene deletion of theleukotoxin CA (lktCA) genomic locus, resulting in an attenuatedbacterium, which secretes a truncated, noncytotoxic form of LktAprotein. The vaccines ideally provide safe, effective, and broadprotective immunity.

Another object of the disclosure is to provide multi-valent vaccines,comprising the attenuated M. haemolytica in combination with otherbacteria, including P. multocida, M. haemolytica serotype A6, andHistophilus somni (H. Somni). Thus, the invention encompasses a 4-wayavirulent, modified live vaccine useful against bovine respiratorydisease.

A further object of this invention is to provide methods for treatmentand prophylaxis of infection bovine respiratory disease, comprising thesteps of administering effective amounts of the inventive vaccines tosusceptible bovine animals.

In one embodiment, the attenuated vaccines further comprises anadjuvant. The adjuvant may be any substance which increases and/oraugments the elicited immune response, as compared to attenuated vaccinealone. Mucosal adjuvants, including chitosans and derivatives thereof,are particularly useful for the disclosed oral attenuated vaccines.

The invention further provides methods for inducing an immunological (orimmunogenic) or protective response against M. haemolytica, as well asmethods for preventing or treating M. haemolytica, or disease state(s)caused by M. haemolytica, comprising administering the attenuatedbacteria, or a composition comprising the attenuated bacteria to animalsin need thereof.

In addition, the disclosure provides PCR methods and reagents useful fordiagnosing and/or discriminating between M. haemolytica serotypes A1 andA6. Comparative genomic sequence analysis, further described below,revealed A1- and A6-specific genes, which provide the basis for themethods and reagents provided in this disclosure.

Kits comprising at least the attenuated M. haemolytica strain andinstructions for use are also provided.

These and other embodiments are disclosed or are obvious from andencompassed by, the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, to one of ordinary skill in the art, is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures, wherein:

FIG. 1 presents the scheme used to produce the pCT109GA189ΔlktCA-Kanplasmid (replacement plasmid). The final product for vaccine manufactureincorporated a consensus ribosome-binding site (AGGAGG, rbs) upstream ofthe start codon which replaced the poor lktC rbs and increasedexpression of leukotoxoid. The native lktA gene, deleted in the vaccinestrain, uses a strong rbs (AGGAGA). For this product, lktRBSr primer wasused in-lieu of lktCAdelr primer. The consensus site is underlined;

FIG. 2 illustrates integration of the replacement plasmid into thebacterial genome;

FIG. 3 depicts resolution/excision of the replacement plasmid, leavingbehind only the desired ΔlktCA sequence, stably integrated into thebacterial genome, and encoding the truncated LktA protein;

FIG. 4A agarose gel electrophoresis of PCR products from M. haemolyticaLktCABD operon showing truncated LktCA (lane 2) and wildtype LktCA (lane3);

FIG. 4B Western blot analysis of truncated LktA expressed by M.haemolytica D153Δ-1-PKL, vaccine strain. Lanes: 1—marker; 2—5 μl ofculture supernatant containing truncated LktA (*=27 kDa, M. haemolyticaD153Δ-1-PKL); 3—5 μl of culture supernatant containing wildtype LktA(*=102 kDa, M. haemolytica D153 parent strain);

FIG. 5 is a Venn diagram representing the unique and overlapping genespresent in five M. haemolytica isolates.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a M. haemolytica vaccine or compositionwhich may comprise an attenuated M. haemolytica strain and apharmaceutically or veterinarily acceptable carrier, excipient, orvehicle, which elicits, induces or stimulates a response in an animal.

In order to develop an effective M. haemolytica intranasal vaccine,which protects bovines against serogroups A1/A6, inventors used M.haemolytica having a partially deleted LktA gene. This bacterium doesnot cause cytolysis, but is able to elicit neutralizing antibodies.Prior to the instant disclosure, it was not known whether intranasaladministration (or administration via any route) would elicit in bovinesa protective immune response.

Although there are serological methods to distinguish M. haemolytica A1and A6 these methods are not always reliable and developing strongantisera against A6 is particularly difficult. To overcome this problem,inventors sequenced both A1 and A6 genomes, performed a comparativegenomic analysis and developed a real time quantitative polymerase chainreaction (RT-QPCR) method to distinguish between A1 and A6 fieldisolates and to track our intranasal vaccine combination (M.haemolytica, M. somnus, and P. multocida).

Thus, an embodiment of this disclosure provides useful RT-QPCR methods,which enable at least the following activities: a) identification offield isolates of M. haemolytica A1 and A6 quickly and screen largenumber of colonies; b) monitoring of vaccination/colonization of A1 andA6 in nasal cavities; c) elimination of the need for developing hightiter antisera; and d) development of rapid, automated diagnostic testkits.

The present invention further provides attenuated M. haemolytica strainshaving a deletion in at least one virulence gene. In an embodiment, thedeletion is within LktCA, a locus that encodes an enzyme acylase (LktC)and leukotoxin A (LktA), the chief cytotoxin. This deletion may beamplified by polymerase chain reaction (PCR) and the secretion of atruncated LktA can be detected on a Western blot to determine if thebacterium is the mutant or wildtype.

Deletion of genomic sequence(s) from virulent parental bacteria toproduce avirulent, attenuated mutant bacteria is accomplished throughnovel and non-obvious inventive activity. Such mutant bacteria, alsoreferred to herein as modified-live microorganisms (MLM) are useful forthe production of immunogenic compositions or vaccines having both ahigh degree of immunogenicity and a low (to non-existent) degree ofpathogenicity.

These mutants are also useful as vectors which can be useful forexpression in vitro of expression products, as well as for reproductionor replication of nucleotide sequences (e.g., replication of DNA), andfor in vivo expression products.

Engineering of the deletion mutations provides novel and nonobviousnucleotide sequences and genes, as well as novel and nonobvious geneproducts encoded by the nucleotide sequences and genes. Such geneproducts provide antigens, immunogens and epitopes, and are useful asisolated gene products. Such isolated gene products, as well as epitopesthereof, are also useful for generating antibodies, which are useful indiagnostic applications.

Such gene products, which can provide or generate epitopes, antigens orimmunogens, are also useful for immunogenic or immunologicalcompositions, as well as vaccines.

In an aspect, the invention provides bacteria containing an attenuatingmutation in a nucleotide sequence or a gene wherein the mutationmodifies, reduces or abolishes the expression and/or the biologicalactivity of a polypeptide or protein encoded by a gene, resulting inattenuated virulence of the bacterium. In a particular embodiment, themutation is an in-frame deletion resulting in the bacterium secreting atruncated leukotoxin. In a particular embodiment, the truncatedleukotoxin migrates at about 27 kD on a typical SDS gel.

Attenuation reduces or abolishes the pathogenicity of the bacteria andthe gravity of the clinical signs or lesions, decreases the growth rateof the bacteria, and prevents the death from the bacteria.

In particular, the present invention encompasses attenuated M.haemolytica strains and vaccines comprising the same, which elicit animmunogenic response in an animal, particularly the attenuated M.haemolytica strains that elicit, induce or stimulate a response in abovine.

Particular M. haemolytica attenuated strains of interest have mutationsin genes, relative to wild type virulent parent strain, which areassociated with virulence. It is recognized that, in addition to strainshaving the disclosed mutations, attenuated strains having any number ofmutations in the disclosed virulence genes can be used in the practiceof this invention.

In another aspect, the novel attenuated M. haemolytica strains areformulated into safe, effective vaccine against M. haemolytica andinfections/diseases cause by M. haemolytica.

In an embodiment, the M. haemolytica vaccines further comprise anadjuvant. In a particular embodiment, the adjuvant is a mucosaladjuvant, such as chitosan, methylated chitosan, trimethylated chitosan,or derivatives or combinations thereof.

As defined herein, the term “gene” will be used in a broad sense, andshall encompass both coding and non-coding sequences (i.e. upstream anddownstream regulatory sequences, promoters, 5′/3′ UTR, introns, andexons). Where reference to only a gene's coding sequence is intended,the term “gene's coding sequence” or “CDS” will be used interchangeablythroughout this disclosure.

By “antigen” or “immunogen” means a substance that induces a specificimmune response in a host animal. The antigen may comprise a wholeorganism, killed, attenuated or live; a subunit or portion of anorganism; a recombinant vector containing an insert with immunogenicproperties; a piece or fragment of DNA capable of inducing an immuneresponse upon presentation to a host animal; a polypeptide, an epitope,a hapten, or any combination thereof. Alternately, the immunogen orantigen may comprise a toxin or antitoxin.

The terms “protein”, “peptide”, “polypeptide” and “polypeptide fragment”are used interchangeably herein to refer to polymers of amino acidresidues of any length. The polymer can be linear or branched, it maycomprise modified amino acids or amino acid analogs, and it may beinterrupted by chemical moieties other than amino acids. The terms alsoencompass an amino acid polymer that has been modified naturally or byintervention; for example disulfide bond formation, glycosylation,lipidation, acetylation, phosphorylation, or any other manipulation ormodification, such as conjugation with a labeling or bioactivecomponent.

The term “immunogenic or antigenic polypeptide” as used herein includespolypeptides that are immunologically active in the sense that onceadministered to the host, it is able to evoke an immune response of thehumoral and/or cellular type directed against the protein. Preferablythe protein fragment is such that it has substantially the sameimmunological activity as the total protein. Thus, a protein fragmentaccording to the invention comprises or consists essentially of orconsists of at least one epitope or antigenic determinant. An“immunogenic” protein or polypeptide, as used herein, includes thefull-length sequence of the protein, analogs thereof, or immunogenicfragments thereof. By “immunogenic fragment” is meant a fragment of aprotein which includes one or more epitopes and thus elicits theimmunological response described above. Such fragments can be identifiedusing any number of epitope mapping techniques, well known in the art.See, e.g., Epitope Mapping Protocols in Methods in Molecular Biology,Vol. 66 (Glenn E. Morris, Ed., 1996). For example, linear epitopes maybe determined by e.g., concurrently synthesizing large numbers ofpeptides on solid supports, the peptides corresponding to portions ofthe protein molecule, and reacting the peptides with antibodies whilethe peptides are still attached to the supports. Such techniques areknown in the art and described in, e.g., U.S. Pat. No. 4,708,871; Geysenet al., 1984; Geysen et al., 1986. Similarly, conformational epitopesare readily identified by determining spatial conformation of aminoacids such as by, e.g., x-ray crystallography and 2-dimensional nuclearmagnetic resonance. See, e.g., Epitope Mapping Protocols, supra. Methodsespecially applicable to the proteins of T. parva are fully described inPCT/US2004/022605 incorporated herein by reference in its entirety.

As discussed herein, the invention encompasses active fragments andvariants of the antigenic polypeptide. Thus, the term “immunogenic orantigenic polypeptide” further contemplates deletions, additions andsubstitutions to the sequence, so long as the polypeptide functions toproduce an immunological response as defined herein. The term“conservative variation” denotes the replacement of an amino acidresidue by another biologically similar residue, or the replacement of anucleotide in a nucleic acid sequence such that the encoded amino acidresidue does not change or is another biologically similar residue. Inthis regard, particularly preferred substitutions will generally beconservative in nature, i.e., those substitutions that take place withina family of amino acids. For example, amino acids are generally dividedinto four families: (1) acidic—aspartate and glutamate; (2)basic—lysine, arginine, histidine; (3) non-polar—alanine, valine,leucine, isoleucine, proline, phenylalanine, methionine, tryptophan; and(4) uncharged polar—glycine, asparagine, glutamine, cystine, serine,threonine, tyrosine. Phenylalanine, tryptophan, and tyrosine aresometimes classified as aromatic amino acids. Examples of conservativevariations include the substitution of one hydrophobic residue such asisoleucine, valine, leucine or methionine for another hydrophobicresidue, or the substitution of one polar residue for another polarresidue, such as the substitution of arginine for lysine, glutamic acidfor aspartic acid, or glutamine for asparagine, and the like; or asimilar conservative replacement of an amino acid with a structurallyrelated amino acid that will not have a major effect on the biologicalactivity. Proteins having substantially the same amino acid sequence asthe reference molecule but possessing minor amino acid substitutionsthat do not substantially affect the immunogenicity of the protein are,therefore, within the definition of the reference polypeptide. All ofthe polypeptides produced by these modifications are included herein.The term “conservative variation” also includes the use of a substitutedamino acid in place of an unsubstituted parent amino acid provided thatantibodies raised to the substituted polypeptide also immunoreact withthe unsubstituted polypeptide.

The term “epitope” refers to the site on an antigen or hapten to whichspecific B cells and/or T cells respond. The term is also usedinterchangeably with “antigenic determinant” or “antigenic determinantsite”. Antibodies that recognize the same epitope can be identified in asimple immunoassay showing the ability of one antibody to block thebinding of another antibody to a target antigen.

An “immunological response” to a composition or vaccine is thedevelopment in the host of a cellular and/or antibody-mediated immuneresponse to a composition or vaccine of interest. Usually, an“immunological response” includes but is not limited to one or more ofthe following effects: the production of antibodies, B cells, helper Tcells, and/or cytotoxic T cells, directed specifically to an antigen orantigens included in the composition or vaccine of interest. Preferably,the host will display either a therapeutic or protective immunologicalresponse such that resistance to new infection will be enhanced and/orthe clinical severity of the disease reduced. Such protection will bedemonstrated by either a reduction or lack of symptoms and/or clinicaldisease signs normally displayed by an infected host, a quicker recoverytime and/or a lowered viral titer in the infected host.

By “animal” is intended mammals, birds, and the like. Animal or host asused herein includes mammals and human. The animal may be selected fromthe group consisting of equine (e.g., horse), canine (e.g., dogs,wolves, foxes, coyotes, jackals), feline (e.g., lions, tigers, domesticcats, wild cats, other big cats, and other felines including cheetahsand lynx), ovine (e.g., sheep), bovine (e.g., cattle), porcine (e.g.,pig), avian (e.g., chicken, duck, goose, turkey, quail, pheasant,parrot, finches, hawk, crow, ostrich, emu and cassowary), primate (e.g.,prosimian, tarsier, monkey, gibbon, ape), ferrets, seals, and fish. Theterm “animal” also includes an individual animal in all stages ofdevelopment, including newborn, embryonic and fetal stages.

Unless otherwise explained, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this disclosure belongs. The singular terms“a”, “an”, and “the” include plural referents unless context clearlyindicates otherwise. Similarly, the word “or” is intended to include“and” unless the context clearly indicate otherwise.

It is noted that in this disclosure and particularly in the claimsand/or paragraphs, terms such as “comprises”, “comprised”, “comprising”and the like can have the meaning attributed to it in U.S. patent law;e.g., they can mean “includes”, “included”, “including”, and the like;and that terms such as “consisting essentially of” and “consistsessentially of” have the meaning ascribed to them in U.S. patent law,e.g., they allow for elements not explicitly recited, but excludeelements that are found in the prior art or that affect a basic or novelcharacteristic of the invention.

The term “nucleic acid” and “polynucleotide” refers to RNA or DNA thatis linear or branched, single or double stranded, or a hybrid thereof.The term also encompasses RNA/DNA hybrids. The following arenon-limiting examples of polynucleotides: a gene or gene fragment,exons, introns, mRNA, tRNA, rRNA, ribozymes, cDNA, recombinantpolynucleotides, branched polynucleotides, plasmids, vectors, isolatedDNA of any sequence, isolated RNA of any sequence, nucleic acid probesand primers. A polynucleotide may comprise modified nucleotides, such asmethylated nucleotides and nucleotide analogs, uracyl, other sugars andlinking groups such as fluororibose and thiolate, and nucleotidebranches. The sequence of nucleotides may be further modified afterpolymerization, such as by conjugation, with a labeling component. Othertypes of modifications included in this definition are caps,substitution of one or more of the naturally occurring nucleotides withan analog, and introduction of means for attaching the polynucleotide toproteins, metal ions, labeling components, other polynucleotides orsolid support. The polynucleotides can be obtained by chemical synthesisor derived from a microorganism.

The term “gene” is used broadly to refer to any segment ofpolynucleotide associated with a biological function. Thus, genesinclude introns and exons as in genomic sequence, or just the codingsequences as in cDNAs and/or the regulatory sequences required for theirexpression. For example, gene also refers to a nucleic acid fragmentthat expresses mRNA or functional RNA, or encodes a specific protein,and which includes regulatory sequences.

An “isolated” biological component (such as a nucleic acid or protein ororganelle) refers to a component that has been substantially separatedor purified away from other biological components in the cell of theorganism in which the component naturally occurs, for instance, otherchromosomal and extra-chromosomal DNA and RNA, proteins, and organelles.Nucleic acids and proteins that have been “isolated” include nucleicacids and proteins purified by standard purification methods. The termalso embraces nucleic acids and proteins prepared by recombinanttechnology as well as chemical synthesis.

The term “conservative variation” denotes the replacement of an aminoacid residue by another biologically similar residue, or the replacementof a nucleotide in a nucleic acid sequence such that the encoded aminoacid residue does not change or is another biologically similar residue.In this regard, particularly preferred substitutions will generally beconservative in nature, as described above.

The term “recombinant” means a polynucleotide with semisynthetic, orsynthetic origin which either does not occur in nature or is linked toanother polynucleotide in an arrangement not found in nature.

“Heterologous” means derived from a genetically distinct entity from therest of the entity to which it is being compared. For example, apolynucleotide may be placed by genetic engineering techniques into aplasmid or vector derived from a different source, and is a heterologouspolynucleotide. A promoter removed from its native coding sequence andoperatively linked to a coding sequence other than the native sequenceis a heterologous promoter.

The polynucleotides of the invention may comprise additional sequences,such as additional encoding sequences within the same transcriptionunit, controlling elements such as promoters, ribosome binding sites,5′UTR, 3′UTR, transcription terminators, polyadenylation sites,additional transcription units under control of the same or a differentpromoter, sequences that permit cloning, expression, homologousrecombination, and transformation of a host cell, and any such constructas may be desirable to provide embodiments of this invention.

Methods of Use and Article of Manufacture

The present invention includes the following method embodiments. In anembodiment, a method of vaccinating an animal comprising administering acomposition comprising an attenuated M. haemolytica strain and apharmaceutical or veterinarily acceptable carrier, excipient, or vehicleto an animal is disclosed. In one aspect of this embodiment, the animalis a bovine.

The dose volume of compositions for target species that are mammals,e.g., the dose volume of pig or swine compositions, based on bacterialantigens, is generally between about 0.1 to about 2.0 ml, between about0.1 to about 1.0 ml, and between about 0.5 ml to about 1.0 ml.

The efficacy of the vaccines may be tested about 2 to 4 weeks after thelast immunization by challenging animals, such as bovine, with avirulent strain of M. haemolytica. Both homologous and heterologousstrains are used for challenge to test the efficacy of the vaccine. Theanimal may be challenged by IM or SC injection, spray, intra-nasally,intra-ocularly, intra-tracheally, and/or orally. Samples from joints,lungs, brain, and/or mouth may be collected before and post-challengeand may be analyzed for the presence of M. haemolytica-specificantibody.

The compositions comprising the attenuated bacterial strains of theinvention used in the prime-boost protocols are contained in apharmaceutically or veterinary acceptable vehicle, diluent or excipient.The protocols of the invention protect the animal from M. haemolyticaand/or prevent disease progression in an infected animal.

The various administrations are preferably carried out 1 to 6 weeksapart. Preferred time interval is 3 to 5 weeks, and optimally 4 weeksaccording to one embodiment, an annual booster is also envisioned. Theanimals, for example pigs, may be at least 3-4 weeks of age at the timeof the first administration.

It should be understood by one of skill in the art that the disclosureherein is provided by way of example and the present invention is notlimited thereto. From the disclosure herein and the knowledge in theart, the skilled artisan can determine the number of administrations,the administration route, and the doses to be used for each injectionprotocol, without any undue experimentation.

Another embodiment of the invention is a kit for performing a method ofeliciting or inducing an immunological or protective response against M.haemolytica in an animal comprising an attenuated M. haemolyticaimmunological composition or vaccine and instructions for performing themethod of delivery in an effective amount for eliciting an immuneresponse in the animal.

Another embodiment of the invention is a kit for performing a method ofinducing an immunological or protective response against M. haemolyticain an animal comprising a composition or vaccine comprising anattenuated M. haemolytica strain of the invention, and instructions forperforming the method of delivery in an effective amount for elicitingan immune response in the animal.

Yet another aspect of the present invention relates to a kit forprime-boost vaccination according to the present invention as describedabove. The kit may comprise at least two vials: a first vial containinga vaccine or composition for the prime-vaccination according to thepresent invention, and a second vial containing a vaccine or compositionfor the boost-vaccination according to the present invention. The kitmay advantageously contain additional first or second vials foradditional prime-vaccinations or additional boost-vaccinations.

The pharmaceutically or veterinarily acceptable carriers or vehicles orexcipients are well known to the one skilled in the art. For example, apharmaceutically or veterinarily acceptable carrier or vehicle orexcipient can be a 0.9% NaCl (e.g., saline) solution or a phosphatebuffer. Other pharmaceutically or veterinarily acceptable carrier orvehicle or excipients that can be used for methods of this inventioninclude, but are not limited to, poly-(L-glutamate) orpolyvinylpyrrolidone. The pharmaceutically or veterinarily acceptablecarrier or vehicle or excipients may be any compound or combination ofcompounds facilitating the administration of the vector (or proteinexpressed from an inventive vector in vitro); advantageously, thecarrier, vehicle or excipient may facilitate transfection and/or improvepreservation of the vector (or protein). Doses and dose volumes areherein discussed in the general description and can also be determinedby the skilled artisan from this disclosure read in conjunction with theknowledge in the art, without any undue experimentation.

The immunological compositions and vaccines according to the inventionmay comprise or consist essentially of one or more adjuvants. Suitableadjuvants for use in the practice of the present invention are (1)polymers of acrylic or methacrylic acid, maleic anhydride and alkenylderivative polymers, (2) immunostimulating sequences (ISS), such asoligodeoxyribonucleotide sequences having one or more non-methylated CpGunits (Klinman et al., 1996; WO98/16247), (3) an oil in water emulsion,such as the SPT emulsion described on page 147 of “Vaccine Design, TheSubunit and Adjuvant Approach” published by M. Powell, M. Newman, PlenumPress 1995, and the emulsion MF59 described on page 183 of the samework, (4) cationic lipids containing a quaternary ammonium salt, e.g.,DDA (5) cytokines, (6) aluminum hydroxide or aluminum phosphate, (7)saponin or (8) other adjuvants discussed in any document cited andincorporated by reference into the instant application, or (9) anycombinations or mixtures thereof.

In an embodiment, adjuvants include those which promote improvedabsorption through mucosal linings. Some examples include MPL, LTK63,toxins, PLG microparticles and several others (Vajdy, M. Immunology andCell Biology (2004) 82, 617-627). In an embodiment, the adjuvant may bea chitosan (Van der Lubben et al. 2001; Patel et al. 2005; Majithiya etal. 2008; U.S. Pat. No. 5,980,912).

In an embodiment, the adjuvant may be inactivated bacteria, aninactivated virus, fractions of inactivated bacteria, bacteriallipopolysaccharides, bacterial toxins, or derivatives or

REFERENCES

-   Ackermann, M. R, Brogden, K. A. 2000. Response of the ruminant    respiratory tract to Mannheimia (Pasteurella) haemolytica. Microbes    Infect. 2:1079-1088.-   Al-Ghamdi, G. M., et al, 2000. Serotyping of Mannheimia    (Pasteurella) haemolytica isolates from the upper Midwest United    States. J. Vet. Diagn. Invest. 12, 576-578.-   Bowland, S., Shewen, P., 2000. Bovine respiratory disease:    commercial vaccines currently available in Canda. Can. Vet. J. 41,    33-38.-   Briggs R. E, Tatum F. M. 2005. Generation and molecular    characterization of new temperature-sensitive plasmids intended for    genetic engineering of Pasteurellaceae. Appl Environ Micobiol    71:7187-7195.-   Burriel, A. R. 1997. News & Notes: Isolation of Pasteurella    haemolytica from Grass, Drinking Water, and Straw Bedding Used by    Sheep. Curr. Microbiol. 35: 316-318.-   Confer, A. W., et al., 2003. Immunogenicity of recombinant    Mannheimia haemolytica serotype 1 outer membrane protein P1pE and    augmentation of a commercial vaccine. Vaccine 21, 2821-2829.-   Davies, R. L, et al. 2002. Mosaic structure and molecular evolution    of the leukotoxin operon (lktCABD) in Mannheimia (Pasteurella)    haemolytica, Mannheimia glucosida, and Pasteurella trehalosi. J    Bacteriol. 184(1):266-277.-   Davies, R. L, et al. 2001. Sequence diversity and molecular    evolution of the leukotoxin (lktA) gene in bovine and ovine strains    of Mannheimia (Pasteurella) haemolytica. J Bacteriol.    183(4):1394-1404.-   Ellis, J., et al., 2007. Response of calves to challenge exposure    with virulent bovine respiratory syncytial virus following    intranasal administration of vaccines formulated for parenteral    administration. J. Am. Vet. Med. Assoc. 230, 233-243.-   Frank, G. H, et al. 2003. Effect of intranasal exposure to    leukotoxin-deficient Mannheimia haemolytica at the time of arrival    at the feedyard on subsequent isolation of M. haemolytica from nasal    secretions of calves. Am J Vet Res. 64(5):580-585.-   Gioia, J. et al. 2006. The genome sequence of Mannheimia haemolytica    A1: insights into virulence, natural competence, and Pasteurellaceae    phylogeny. J Bacteriol. 188(20):7257-7266.-   Lawrence, P. K., et al., 2010. Three-way comparative genomic    analysis of two Mannheimia haemolytica isolates. BMC Genomics.    11:535 (Open access).-   Morton, R. J., et al., 1995. Vaccination of cattle with outer    membrane protein-enriched fractions of Pasteurella haemolytica and    resistance against experimental challenge exposure. Am. J. Vet. Res.    56, 875-879.-   Miller, M. W. 2001. Pasteurellosis, In E. S. Williams and I. K.    Barker (ed.), Infectious diseases of wild mammals. Iowa State    University. Press, Ames, Iowa p. 330-339-   Mosier, D. A. 1997. Bacterial pneumonia. Vet. Clin. N. Am. Food    Anim. Pract. 13:483-493.-   Muylkens, B., et al., 2007. Bovine herpesvirus 1 infection and    infectious bovine rhinotracheitis. Vet. Res. 38, 181-209.-   Potter, A. A., et al., 1999. Protective capacity of the Pasteurella    haemolytica transferrin-binding proteins TbpA and TbpB in cattle.    Microb Pathog 27, 197-206.-   Perino, L. J., Hunsaker, B. D., 1997. A review of bovine respiratory    disease vaccine field efficacy. The Bovine Practitioner 31, 59-66.-   Purdy, C. W., et al, 1993. Efficacy of Pasteurella haemolytica    subunit antigens in a goat model of pasteurellosis. Am. J. Vet. Res.    54, 1637-1647.-   Purdy, C. W., et al., 1997. Efficacy of a subcutaneously    administered, ultraviolet light-killed Pasteurella multocida    A:3-containing bacterin against transthoracic challenge exposure in    goats. Am. J. Vet. Res. 58, 841-847.-   Rehmtulla, A. J, Thomson, R. G. 1981. A review of the lesions in    shipping fever of cattle. Can. Vet. J. 22:1-   Rice, J. A., et al., 2007. Mannheimia haemolytica and bovine    respiratory disease. Anim. Health Res. Rev. 8, 117-128.-   Sabri, M. Y., et al., 2000. Efficacy of an outer membrane protein of    Pasteurella haemolytica A2, A7 or A9-enriched vaccine against    intratracheal challenge exposure in sheep. Vet. Microbiol. 73,    13-23.-   Schreuer, D., et al. 2000. Evaluation of the efficacy of a new    combined (Pasteurella) Mannheimia haemolytica serotype A1 and A6    vaccine in pre-ruminant calves by virulent challenge. Journal Cattle    Practice Vol. 8 No. 1 pp. 9-12-   Shewen, P. E., Wilkie, B. N., 1988. Vaccination of calves with    leukotoxic culture supernatant from Pasteurella haemolytica. Can. J.    Vet. Res. 52, 30-36.-   Virtala, A. M., et al., 1996. Epidemiologic and pathologic    characteristics of respiratory tract disease in dairy heifers during    the first three months of life. J. Am. Vet. Med. Assoc. 208,    2035-2042.

The invention will now be further described by way of the followingnon-limiting examples.

EXAMPLES Example 1 Production of Attenuated M. haemolytica

M. haemolytica is a commensal organism of the upper respiratory tract ofcalves and other ruminants. Under stress and in immunocompromisedanimals M. haemolytica descends into lungs and causes severe systemicdisease resulting in pneumonic pasteurellosis or “shipping fever”. Thepathogen can be spread by nose to nose contact. To attenuate thebacterium, we deleted nucleotides within the LktCA locus, which encodesan enzyme acylase (LktC) and leukotoxin A (LktA), the bacterium's chiefcytotoxin. This deletion can be amplified by polymerase chain reaction(PCR) and the secretion of a truncated LktA can be detected on a Westernblot to determine if the bacterium is the mutant or wildtype. Thegenetic engineering is summarized in FIGS. 1-3. All reagents, includingthe shuttle vectors pCR2.1, pBC SK, pSK, and pCT109GA189 is ori, and theE. coli DH11S host cell, are well-known to and accessible by personsskilled in the art.

Construction of lktCA Deletion.

pCT109GA189-KanΔlktCA and pCT109GA189-KanΔlktCA-rbs were constructed asoutlined in FIGS. 1-3. Briefly, two DNA fragments, upstream (1.06 kb,SEQ ID NO:6) and downstream (1.29 kb, SEQ ID NO:7) were PCR amplifiedfrom M. haemolytica strain NADC D153 (FIG. 1). Whole cells were used astemplate using the primer sets, lktCAf (SEQ ID NO:1)/lktCAdelr (SEQ IDNO:4) and lktCAr (SEQ ID NO:2)/lktCAdelf (SEQ ID NO:3). The PCR productswere phenol-chloroform-extracted to inactivate Taq polymerase and thendigested with MunI prior to ligation. The ligation products were PCRamplified with primer pair lktCAf/lktCAr and the products were clonedusing a commercially available vector (PCR2.1, Invitrogen, Carlsbad,Calif.) according to manufacturer instructions.

A product containing an approximately 2.3 kb insert was selected andproper sequence across the deletion was confirmed by DNA sequencing anddesignated pTAΔlktCA. A kanamycin cassette derived from pUC4K was placedinto the SalI site of pBC SK- (Stratagene Inc.) to generate pBCKan. The2.3 kb deleted leukotoxin insert in pTAΔlktCA was transferred intopBCKan by digestion with EcoRI and ligation into the unique EcoRI siteto form pBCKanΔlktCA. This product was amplified by PCR using primerpair lktCAdelf (SEQ ID NO:3) and lktRBSr (SEQ ID NO:5) to replace thenative lktC ribosome binding site (RBS) with a consensus RBS (FIG. 1).The product was digested with MunI and ligated onto itself to formpBCKanΔlktCArbs. Proper sequence adjacent to the deletion was confirmedby DNA sequencing. Finally the pBC plasmid backbone of both pBCKanΔlktCAand pBCKanΔlktCArbs was replaced with the temperature-sensitive plasmidorigin of replication from pCT109GA189 (Briggs and Tatum, 2005) byligating BssHII-digested preparations of each to generatepCT109GA189KanΔlktCA and pCT109GA189KanΔlktCArbs.

Electrocompetent M. haemolytica serotype A1 D153 cells (virulentparental strain) were transformed with pCT109GA189KanΔlktCA andpCT109GA189KanΔlktCArbs by previously described methods exceptunmethylated ligation product was directly introduced into the competentcells. (Briggs and Tatum, 2005) Briefly, cells were madeelectrocompetent by growing them to logarithmic phase in 100 ml ofColumbia broth (Difco Laboratories, Detroit, Mich.) at 37° C. withgentle shaking. The cells were pelleted by centrifugation at 5,000 μgand washed in 100 ml of 272 mM sucrose at 0° C., and the pellet wassuspended in an equal volume of 272 mM sucrose at 0° C. Afterelectroporation, cells recovered overnight in 10 ml Columbia broth at30° C. Growth (50 μl) was spread onto Columbia agar plates containing 50μg/ml kanamycin, which were then incubated 36 hours at 30° C. Individualcolonies were passed to broth containing 50 μg/ml kanamycin andincubated overnight at 30° C. Growth (100 μl) was passed again toColumbia agar plates with kanamycin which were incubated overnight at39° C. Individual colonies were passed to trypticase soy agar (TSA)plates containing 5% defibrinated sheep blood (BA plates, incubatedovernight at 39° C.) and to Columbia broth without selection (incubatedovernight at 30° C.). Growth in broth was streaked for isolation on BAplates and passed again in broth at 30° C. Non-hemolytic colonies whichwere kanamycin-sensitive were detected on BA plates after 1 to 3passages without selection. Representative colonies from each recipientstrain and replacement plasmid were selected for further study.

Because the temperature-sensitive plasmid origin functions poorly in E.coli cloning hosts, these final ligation products were introduceddirectly into M. haemolytica. Prior cloning steps used E. coli DH11S(Life Technologies, Rockville, Md.) as the cloning host.

Non-hemolytic mutants were grown in Columbia broth at 37° C. for 3 hoursand harvested in late logarithmic growth. Supernatants were dotted ontonitrocellulose along with supernatants from the wild-type parent and aleukotoxin-negative isogenic mutant. After appropriate blocking andwashing, the blot was probed with monoclonal anti-leukotoxin antibody2C9-1E8 (neutralizing antibody produced by NADC, Ames, Iowa). Mutantproducts containing the native ribosome binding site were found toexpress low levels of protein reactive to monoclonal antibody, less thanthat produced by the wild-type parent strain. Products which containedthe new ribosome binding site produced much higher levels of reactiveprotein. Supernatants of two products expressing high levels ofleukotoxin were concentrated 15-fold on a 10,000 MW filter (Centriprep,Amicon). The concentrates (1.5 μl) were subjected to SDS-PAGE, blottedto nitrocellulose, and probed with antibody 2C9-1E8. Western blotanalysis indicated a new protein reactive with neutralizinganti-leukotoxin monoclonal antibody at an apparent molecular weightconsistent with the 27 kDa predicted protein (truncated LktA) product.These representative mutants and single-crossover controls were analyzedby PCR to demonstrate the absence of temperature-sensitive origin andkanamycin-resistance cassette (Step G). The mutant M. haemolyticaserotype A1 was designated as D153ΔlktCA4-707, which refers to the aminoacid positions in LktC and LktA respectively where the deleted regionbegins and ends. Gene insertion was characterized by PCR amplificationusing LktCAf (SEQ ID NO:1) and LktCAr (SEQ ID NO:2) primers, which flankthe deletion site. As indicated by the gel image, PCR amplificationyielded the expected ˜2.3 kb for truncated LktCA, and ˜5.0 kb for thewildtype bacterium (FIG. 4A). Finally, PCR performed with primers (SEQID NOs:1 & 2) flanking is on and kanamycin resistance genes confirmedthose elements were no longer present in the final LktCA mutant forMaster Seed (MS). Five microliters of the concentrated culturesupernatant was run on a SDS-PAGE system, blotted onto PVDF membrane andprobed using mouse anti-LktA, neutralizing antibody 2C9-1E8 (1:1000) asprimary antibody. Goat anti-mouse IgG (1:4000) coupled with alkalinephosphatase was used as secondary antibody and developed in a substratesolution containing NBT/BCIP for 1-5 min (FIG. 4B). The lack offunctional acylase prevents the activation of LktA, and furthermore, theN-terminal deletion of LktA prevents it from forming pores on hostanimal neutrophils or macrophages.

Example 2 Efficacy of Attenuated M. haemolytica in Calves

Calves were randomly assigned to one of three groups, each receivingeither 10⁶ or 10⁷ CFU of the MH A1+A6 vaccine, or the control RPMI(diluent). Lyophilized Mannheimia haemolytica (MH) serotypes A1 and A6were resuspended and administered intranasally, 1 mL to each nostril, ofnine calves, aged 5-6 weeks. The calves were observed for feed intakeand rectal temperatures taken morning and evening for 3 days postvaccination. Nasal colonization of M. haemolytica A1 and A6 followingvaccination was analyzed by RT-QPCR (differentiated among M. haemolyticaA1 and A6 throughout the study). Vaccines were plated on TSA for exactCFU/ml count on each vaccine the following day.

Challenge.

A fresh glycerol stock of virulent MH A1 was grown O/N in BHI medium,plated (TSA) the next day and incubated at 37° C. The following day,plates were scraped and diluted into RPMI medium supplemented with 2%inactivated fetal bovine serum. The inoculum was grown at 37° C./200 rpmuntil desired OD₆₀₀ was achieved, and the culture was diluted to thedesired CFU/challenge dose and dilution plated to enumerate the exactCFU/ml the following day. The remaining inoculum was immediatelydilution plated in the lab. Calves were challenged on DAY viatrans-tracheal administration of 2.4×10⁹ CFU in 20 ml RPMI, chased with60 ml RPMI. The calves were monitored for change in behavior includinglethargy, coughing, nasal discharge and scored as shown in Table 3.Rectal temperatures were monitored for calves showing clinical signs.The lungs were scored for pneumonic lesions and recorded as % lesion oneach lobe, and lung tissue was also collected for histopathology. Swabswere taken from lung lesions and trachea to recover the challengeorganism. Table 1 presents the study schedule.

TABLE 1 Study schedule Age Day Event 5-6 0 Day 0-Bleed, Swab andvaccinate intra-nasally weeks 7 7 days post vax-Bleed and swab old 14 14days post vax-Bleed and swab 21 21 days post vax-Bleed and swab 22 22days post vax-Bleed, swab & Challenge with M. haemolytica A1 22-29Observe clinical signs starting 8/7, euthanize any calves if necessary.Euthanize and necropsy all on 8/13 *Calves were observed for feed intakeand rectal temperatures (morning/evening) for 3 days, post vaccination.Samples from each calf were tested using whole cell, Lkt ELISA andRT-QPCR.

TABLE 2 Clinical signs criteria 0 = Normal 1 = Depression, Anorexia,Cough, Nasal Discharge, Dyspnea 2 = Severely Depressed, Unable to Riseor Walk, Euthanized for Humane Reasons 3 = Dead On Arrival (DOA)

Results.

Three days post challenge one of the control calves showed severe signsof pneumonia and was euthanized (36.92% typical M. haemolytica lesions).The remaining 8 calves were euthanized on day 6 and their percent lunginvolvement is described in Table 3. The results clearly indicate thatthe vaccine affords protection when administered intranasally. Asindicated in table 4 intranasal vaccination of M. haemolytica A1/A6combo significantly reduced (62.0% and 76.7% for 6 log and 7 log grouprespectively) the lung lesions when compared to sham. Furthermore,histopathological analysis clearly indicated typical necrotizingbronchopneumonia characteristic of M. haemolytica.

TABLE 4 Actual vaccine dose Lung Average lung Average % reduction inlung Animal # A1/A6 CFU/animal lesion (%) lesion (%) lesion compared tosham 125 1.19 × 10⁶/9.2 × 10⁵ 24.03 176 1.19 × 10⁶/9.2 × 10⁵  0.0 1881.19 × 10⁶/9.2 × 10⁵  6.40 10.43 62.0 179 1.19 × 10⁷/9.2 × 10⁶  0.87 1851.19 × 10⁷/9.2 × 10⁶  1.837 189 1.19 × 10⁷/9.2 × 10⁶ 14.91* 6.48 76.7122 Sham  8.85 177 Sham 37.75 182 Sham 36.92 27.84 The lesions (grosspathology) were due to typical Mycoplasma bovis chronic infection

Example 3 Development of RT-QPCR Method for Distinguishing Between A1/A6Serotypes

The efficacy of intranasal colonization of M. haemolytica A1/A6 wasfollowed during the course of experiment by a novel QPCR method.Briefly, the genomes of above-described A1 and A6 serotype bacteria werecompared against one A1 and two A2 genomes available in GenBank. Thecomparison revealed 63 genes specific for A1 (D153) and 42 genesspecific for A6 (D174). Out of these 105 genes we picked a S6 familyIgA-specific metalloendopeptidase (SEQ ID NO:14) specific for A1 andBCCT family betaine/carnitine/choline transporter gene (SEQ ID NO:12)specific for A6 respectively for differential real time PCR. These genesequences were amplified by using gene specific primers, sequenced bystandard Sanger method and verified. Next, we designed real time PCRprimers and tagged the probes with two different dyes (A1-5′6 FAM/ZEN/3and A6-5′Cy5/3′IBRQ) within each gene. To verify the efficacy our assaymethod we picked M. haemolytica colonies from nasal swabs obtained fromcalves maintained in our facilities 7 days post vaccination. Theindividual colonies were amplified by multiplex real time colony PCRusing QuantiTect Probe PCR kit mastermix (Qiagen) following themanufacturer's instruction in a MX3000P qPCR machine (Stratagene). A1and A6 colonies verified by serotyping were used as positive controlsfor multiplex real time quantitative PCR (RT-QPCR). The ct values wereset at machine default setting and each colony verified by multiplexreal time PCR was confirmed by leukotoxin (LktA) specific PCR. TheRT-QPCR results 7 days post vaccination indicated a preferentialcolonization of A1 over A6 (Table 5), which was further confirmed byleukotoxin gene specific deletion PCR (Table 6). But 14 and 21 days postvaccination indicated essentially exclusive colonization of A1 (Tables 7& 8).

TABLE 5 RT-QPCR results for nasal swabs from D7 Post Vaccination ID A1A6 ΔLkt 151-1 17 11 + 151-2 15 − + 151-3 16 − + 151-4 17 − + 151-5 15− + 154-1 − − 154-2 − 39 154-3 − − 154-4 − − 154-5 − 22 157-1 15 − +157-2 22 − + 157-3 17 − + 157-4 15 33 + 157-5 16 − + 160-1 18 13 + 160-2− 12 + 160-3 − 12 + 160-4 − 12 + 160-5 − 11 + 178-1 − − 178-2 − − 178-3− − 178-4 − 24 178-5 − 31 181-1 15 15 + 181-2 17 − + 181-3 − 13 + 181-417 − + 181-5 15 − + 183-1 16 12 + 183-2 − 35 183-3 17 − + 183-4 16 − +183-5 − 17 + 186-1 − 42 186-2 − 43 186-3 − − 186-4 − − 186-5 − 20 190-1− − 190-2 − − 190-3 − 10 190-4 − − 190-5 − − 193-1 15 38 + 193-2 15 − +193-3 − 36 193-4 16 20 + 193-5 − − A1 mut. Vx 15 − + A6 mut. Vx − 11 +Neg − −

TABLE 6 PCR results for nasal swabs from D7 Post Vaccination ID/colonyA1 A6 Lkt Δ ~2300 bp 122-1 − − 122-2 − − 122-3 − − 122-4 − − 122-5 − −125-1 16 − + Y 125-2 17 − + Y 125-3 17 − + Y 125-4 16 − + Y 125-5 17 − +Y 176-1 17 − + Y 176-2 17 − + Y 176-3 16 − + Y 176-4 16 − + Y 176-5 16− + Y 177-1 − − 177-2 − − 177-3 − − 177-4 − − 177-5 − − 179-1 17 − + Y179-2 16 − + Y 179-3 − − 179-4 16 − + Y 179-5 29 − + Y 182-1 − − 182-2 −− 182-3 − − 182-4 − − 182-5 − − 185-1 − 15 + Y 185-2 18 − + Y 185-3 16− + Y 185-4 − − + Y 185-5 22 − + Y 188-1 − − 188-2 − − 188-3 − − 188-4 −− 188-5 − − 189-1 16 − + Y 189-2 16 − + Y 189-3 21 − + Y 189-4 16 − + Y189-5 17 − + Neg − −

TABLE 7 PCR results for nasal swabs from D14 Post Vaccination ID-colony# A1 A6 Lkt Δ PCR Lkt Δ 122-1 (Con. 0 0 Neg 122-2 (Con. 0 0 Neg 122-3(Con. 0 0 Neg 125-1 (6 log) 15 0 Pos Y 125-2 (6 log) 16 0 Pos Y 125-3 (6log) 16 0 Pos Y 176-1 (6 log) 0 0 Neg 176-2 (6 log) 0 0 Neg 176-3 (6log) 0 0 Neg 177-1 (Con. 0 0 Neg 177-2 (Con. 0 0 Neg 177-3 (Con. 0 0 Neg179-1 (7 log) 0 0 Neg 179-2 (7 log) 0 0 Neg 179-3 (7 log) 0 0 Neg 182-1(Con.) 0 0 Neg 182-2 (Con.) 0 0 Neg 182-3 (Con.) 0 0 Neg 185-1 (7 log) 00 Neg 185-2 (7 log) 0 0 Neg 185-3 (7 log) 0 0 Neg 188-1 (6 log) 0 0 Neg188-2 (6 log) 0 0 Neg 188-3 (6 log) 0 0 Neg 189-1 (7 log) 15 0 Pos Y189-2 (7 log) 15 0 Pos Y 189-3 (7 log) 15 0 Pos Y A1 Mutant Pos 15 0 PosY A6 Mutant Pos 0 16 Pos Y Neg Con. 0 0 Neg

TABLE 8 PCR results for nasal swabs from D21 Post Vaccination ID-colony# A1 A6 Lkt Δ PCR Lkt Δ 122-1 (Con.) 0 0 Δ 122-2 (Con.) 0 0 122-3 (Con.)0 0 125-1 (6 log 14 0 + Y 125-2 (6 log 15 0 + Y 125-3 (6 log 15 0 + Y176-1 (6 log 15 0 + Y 176-2 (6 log 15 0 + Y 176-3 (6 log 15 0 + Y 177-1(Con.) 0 0 177-2 (Con.) 0 0 177-3 (Con.) 0 0 179-1 (7 log 0 0 179-2 (7log 0 0 179-3 (7 log 0 0 182-1 (Con.) 0 0 182-2 (Con.) 0 0 182-3 (Con.)0 0 185-1 (7 log) 15 0 + Y 185-2 (7 log) 14 0 + Y 185-3 (7 log) 15 0 + Y188-1 (6 log) 14 0 + Y 188-2 (6 log) 15 0 + Y 188-3 (6 log) 14 0 + Y189-1 (7 log) 16 0 + Y 189-2 (7 log) 17 0 + Y 189-3 (7 log) 15 0 + Y A1Mutant Pos 15 0 + Y A6 Mutant Pos 0 16 + Y Neg Control 0 0 neg PreChallenge A1 Wt 15 0 + WT Post Challenge A1 Wt 16 0 + WT

Example 3 Intranasal Vaccination of Calves Using Mannheimia haemolyticaA1 & A6 Vaccines Followed by Virulent Challenge

Fifteen calves, 4 weeks of age and housed in 3 different pens/5 calvesper pen, were randomly assigned to one of the two treatment groups.Calves were vaccinated intranasally with modified live Mannheimiahaemolytica serotypes A1 and A6 (reconstituted from lyophilized. Table9), and intranasal colonization or A1 and A6 was monitored by real timePCR. Calves were finally challenged with virulent M. haemolytica A6(wild type) to determine vaccine efficacy.

TABLE 9 Treatment Groups. Total Dose/CFU Group Treatment per animalRoute/volume Calf Id # 1 M. haemolytica A1 + A6 10⁷ (1.43 × 10⁶ +Intranasal 1 ml per nostril 2, 4, 6 8, 10 8.63 × 10⁵)* 2 M. haemolyticaA1 + A6 10⁸ (1.43 × 10⁷ + Intranasal 1 ml per nostril 1, 3, 5, 7, 9 8.63× 10⁶)* 3 Control-Lyophilized control Intranasal 1 ml per nostril 162,166, 170, 174, RPMI + stabilizer 175 *Actual CFU/ml based on plate count

Vaccination.

Lyophilized cultures of M. haemolytica A1 and A6 were enumerated from abatch stored at 4° C. On vaccination day, the vaccines were diluted inRPMI (colorless) to required CFU/ml for each isolate. Similarly, thesham vaccine (lyophilized RPMI in stabilizer) was diluted in RPMI. Thevaccines were plated on TSA to determine the exact CFU/ml count on eachvaccine the following day. The vaccines were mixed and administered 1ml/nostril using a repeat syringe attached with a cannula according tothe dose in Table 9. The control group was vaccinated first, followed bythe lowest to highest log group. Following vaccination, the samples werecollected as described in Table 10, and the calves were observed forfeed intake and rectal temperatures taken morning and evening for 3 dayspost vaccination. Nasal colonization of M. haemolytica A1 and A6following vaccination was analyzed by Q-PCR as described above.

M. haemolytica A6 challenge culture. A fresh glycerol stock of M.haemolytica A6 was grown O/N in BHI medium, plated (TSA) the next dayand incubated at 37° C. The following day, plates were scraped anddiluted into RPMI medium supplemented with 2% inactivated fetal bovineserum. The inoculum was grown at 37° C./200 rpm until desired OD₆₀₀ wasachieved. The culture was diluted to desired CFU/challenge dose anddilution plated to enumerate the exact CFU/ml the following day. Theinoculum was transported on ice and kept on ice during challenge, andadministered trans-tracheally using a 14G×1 inch needle. The dose was1.09×10⁹ CFU/animal in 20 ml RPMI, chased with 60 ml RPMI. Oncecompleted, the remaining inoculum was immediately dilution plated. Thecalves were monitored for behavior changes including lethargy, coughing,and nasal discharge and scored as shown in Table 11. Rectal temperatureswere monitored for calves showing clinical signs. The lungs were scoredfor pneumonic lesions and recorded as % lesion on each lobe, and tissueswere collected for histopathology. Swabs were also taken from lungs(lesions) and trachea to recover the challenge organism.

TABLE 10 Study Schedule. Age Date Event 4 weeks old 0 Day 0-Bleed, Swaband vaccinate intra-nasally 7 days post vax 7 days post vax-Bleed andswab 15 days post vax 15 days post vax-Bleed and swab & Challenge withM. haemolytica A6 15 to 20 days post Observe clinical signs starting day15; euthanized any calves when vax necessary. Euthanized and necropsyall on day 20 *Feed intake (daily) and rectal temperatures (twice daily)were monitored for 3 days post vaccination.

TABLE 11 Clinical signs. Criteria for Post Challenge Observations 0 =Normal 1 = Depression, Anorexia, Cough, Nasal Discharge, Dyspnea 2 =Severely Depressed, Unable to Rise or Walk, Euthanized for HumaneReasons 3 = Dead On Arrival (DOA)

Results.

Two days post challenge calf #5 and 174 showed severe signs of pneumoniaand were euthanized. Calf #7 died on day 3, post challenge. Theremaining 12 calves were euthanized on day 5 and their % lunginvolvement is described in table 4. The results indicate that 80% ofvaccinates were protected by the modified live M. haemolytica A1/A6vaccine. From the 7 log group, three (1, 3 and 9) animals were protectedwhile the other two animals (5, 7) had significantly large lesionscompared to controls. The large lesions could have been caused by anexisting Mannheimia, mycoplasma or viral infection, which had beenexacerbated by challenge. Overall, 80% of vaccinates (1, 2, 3, 4, 6, 8,9 and 10) had significantly (89.55% reduction) reduced lung lesion ascompared to control, and histopathological analysis indicated typicalnecrotizing bronchopneumonia in the control animals.

TABLE 12 Dosage groups. Average % reduction in Average lung lesionActual A1/A6 Lung lung compared to Animal vaccine dose lesion lesionsham Group # CFU/animal (%) (%) vaccine 10⁷ 2 1.43 × 10⁶/8.63 × 10⁵ 0.04 1.43 × 10⁶/8.63 × 10⁵ 8.67 6 1.43 × 10⁶/8.63 × 10⁵ 5.92 8 1.43 ×10⁶/8.63 × 10⁵ 4.83 10 1.43 × 10⁶/8.63 × 10⁵ 0.0 3.88 85.04 10⁸ 1 1.43 ×10⁷/8.63 × 10⁶ 0.0 3 1.43 × 10⁷/8.63 × 10⁶ 0.0 5 1.43 × 10⁷/8.63 × 10⁶41.58 7 1.43 × 10⁷/8.63 × 10⁶ 64.47 9 1.43 × 10⁷/8.63 × 10⁶ 2.295 21.6614.47 162 Sham 37.11 166 Sham 29.82 170 Sham 11.235 174 Sham 25.54 175Sham 25.97 25.93

The efficacy of intranasal colonization of M. haemolytica A1/A6 wasfollowed during the course of experiment by above-described QPCRmethods. Results for 7 and 15 days post-vaccination indicated vaccinateshad a preferential colonization of A1 over A6 which was furtherconfirmed by leukotoxin gene specific deletion PCR (Tables 13 & 14).

TABLE 13 Day 7 Post Vaccination Sample Animal FAM MH MH CY5 MH # # A1A1? MHA6 A6? 1 1 No Ct 16.5 + 2 1 No Ct 38.26 + 3 1 No Ct 16.53 + 4 1 NoCt 25 + 5 2 No Ct No Ct 6 2 No Ct No Ct 7 2 No Ct No Ct 8 2 17.01 + NoCt 9 3 No Ct 15.87 + 10 3 25.11 + 20.81 + 11 3 21.91 + 19.69 + 12 322.35 + 21.8 + 13 4 16.52 + No Ct 14 4 17.11 + No Ct 15 4 16.26 + No Ct16 4 16 + No Ct 17 5 39.07 + 41.17*Plot was bad~NEG 18 5 15.98 + No Ct19 5 16.4 + No Ct 20 5 16.44 + No Ct 21 6 17.08 + No Ct 22 6 18.24 + NoCt 23 6 16.8 + No Ct 24 6 17.94 + No Ct 25 7 17.98 + No Ct 26 7 No Ct16.34 + 27 7 26.57 + 15.46 + 28 7 16.7 + 17.52 + 29 8 16.7 + No Ct 30 816.71 + No Ct 31 8 16.1 + No Ct 32 8 15.16 + No Ct 33 9 16.32 + No Ct 349 17.03 + No Ct 35 9 16.63 + No Ct 36 9 16.04 + No Ct 37 10 No Ct No Ct38 10 No Ct No Ct 39 10 No Ct No Ct 40 10 No Ct No Ct 41 162 No Ct No Ct42 162 No Ct No Ct 43 162 No Ct No Ct 44 162 No Ct No Ct 45 166 No Ct NoCt 46 166 No Ct No Ct 47 166 No Ct No Ct 48 166 No Ct No Ct 49 170 No CtNo Ct 50 170 No Ct No Ct 51 170 No Ct No Ct 52 170 No Ct No Ct 53 174 NoCt No Ct 54 174 No Ct No Ct 55 174 No Ct No Ct 56 174 No Ct No Ct 57 175No Ct No Ct 58 175 No Ct No Ct 59 175 No Ct No Ct 60 175 No Ct No Ct 61A1 mut + 16.66 No Ct 62 A6 mut + No Ct 13.85 63 A1 Wt + 15.87 No Ct 64Neg 40.77 No Ct

TABLE 14 Day 15 Post Vaccination Animal # FAM MHA1 MHA1? CY5 MHA6 MHA6?Lkt del PCR 1 No Ct 40.53 1 No Ct No Ct 1 No Ct No Ct 1 No Ct No Ct 1 NoCt No Ct 2 No Ct No Ct 2 No Ct No Ct 2 No Ct No Ct 2 No Ct No Ct 2 No CtNo Ct 3 No Ct 15.1 + Mutant 3 No Ct 15.08 + Mutant 3 No Ct 15.19 +Mutant 3 No Ct 15.3 + Mutant 3 No Ct 15.1 + Mutant 4 15.82 No Ct Mutant4 No Ct No Ct 4 No Ct No Ct 4 No Ct No Ct 4 No Ct No Ct 5 16.13 + No CtMutant 5 15.27 + No Ct Mutant 5 17.03 + No Ct Mutant 5 16.49 + No CtMutant 5 18.06 + No Ct Mutant 6 No Ct No Ct 6 No Ct No Ct 6 No Ct No Ct6 40.05 No Ct 6 No Ct No Ct 7 No Ct 16.83 + Mutant 7 No Ct No Ct + 7 NoCt 14.92 + Mutant 7 No Ct 15.21 + Mutant 7 No Ct 16.16 + Mutant 8 No CtNo Ct 8 No Ct No Ct 8 No Ct No Ct 8 No Ct No Ct 8 No Ct No Ct 9 No Ct NoCt 9 No Ct No Ct 9 No Ct No Ct 9 No Ct No Ct 9 No Ct No Ct 10 15.94 + NoCt Mutant 10 No Ct + No Ct 10 No Ct + No Ct 10 23.82 + No Ct Mutant 1030.04 + No Ct Mutant 162 No Ct No Ct 162 No Ct No Ct 162 No Ct No Ct 162No Ct No Ct 162 No Ct No Ct 166 No Ct No Ct 166 No Ct No Ct 166 No Ct NoCt 166 No Ct No Ct 166 No Ct No Ct 170 No Ct No Ct 170 No Ct No Ct 170No Ct No Ct 170 No Ct No Ct 170 No Ct No Ct 174 No Ct No Ct 174 No Ct NoCt 174 No Ct No Ct 174 No Ct No Ct 174 No Ct No Ct 175 16.24 + No CtMutant 175 No Ct + No Ct 175 16.54 + No Ct Mutant 175 No Ct + No CtMutant 175 23.06 + No Ct Mutant

Having thus described in detail preferred embodiments of the presentinvention, it is to be understood that the invention defined by theabove paragraphs is not to be limited to particular details set forth inthe above description as many apparent variations thereof are possiblewithout departing from the spirit or scope of the present invention.

1-23. (canceled)
 24. A gene-deleted M. haemolytica bacterium, useful forthe prevention of bovine respiratory disease, in a bovine animal, causedby M. haemolytica, comprising a deletion within the LktCA gene locusencoding acylase (LKTC) and leukotoxin A (LKTA); and wherein thebacterium secretes a truncated form of a LKTA having an amino acidsequence encoded by the sequence as set forth in SEQ ID NO:16 or
 17. 25.The gene-deleted bacterium of claim 24, wherein the bovines are calves28 days and older.
 26. The gene-deleted bacterium of claim 24, which isattenuated relative to virulent wildtype parental bacterium, and whereinthe parental bacterium causes bronchopneumonia in the lungs of affectedcattle, and has the designation serotype A1 D153.
 27. The gene-deletedbacterium of claim 24, which is attenuated relative to virulent wildtypeparental bacterium, and wherein the parental bacterium causesbronchopneumonia in the lungs of affected cattle, and has thedesignation serotype A6 D174.
 28. The gene-deleted bacterium of claim24, which replicates primarily in a bovine's nasal passages to producean immune response.
 29. The gene-deleted bacterium of claim 24, whereinwhen administered to bovines, no shedding is observed in the animal'sfeces, saliva, or other body fluids.
 30. The gene-deleted bacterium ofclaim 24, which causes no prolonged itching or irritation at the site ofinoculation.
 31. The gene-deleted bacterium of claim 24, which causes noprolonged itching or irritation at the site of inoculation.
 32. A methodof producing a gene-deleted M. haemolytica bacterium that is useful forthe prevention of bovine respiratory disease, in a bovine animal, causedby M. haemolytica, comprising the step of making a deletion within theLKTCA gene locus encoding acylase (LKTC) and leukotoxin A (LKTA);wherein, as a result of the deletion, the bacterium secretes a truncatedform of a LKTA having an amino acid sequence encoded by the sequence asset forth in SEQ ID NO:16 or 17, thereby producing the gene-deletedbacterium.
 33. The method of claim 32, wherein the bovines are calves 28days and older.
 34. The method of claim 32, wherein the gene-deletedstrain is attenuated relative to virulent wildtype parental bacterium,and wherein the parental bacterium causes bronchopneumonia in the lungsof affected cattle, and has the designation serotype A1 D153.
 35. Themethod of claim 32, wherein the gene-deleted strain is attenuatedrelative to virulent wildtype parental bacterium, and wherein theparental bacterium causes bronchopneumonia in the lungs of affectedcattle, and has the designation serotype A6 D174.
 36. The method ofclaim 32, wherein the gene-deleted strain replicates primarily in abovine's nasal passages to produce an immune response.
 37. The method ofclaim 32, wherein the gene-deleted bacterium is administered to bovines,no shedding is observed in the animal's feces, saliva, or other bodyfluids.
 38. The method of claim 32, wherein the gene-deleted bacteriumcauses no prolonged itching or irritation at the site of inoculation.39. The method of claim 32, wherein the gene-deleted bacterium causes noprolonged itching or irritation at the site of inoculation.
 40. A methodof confirming the presence of the deletion in the gene-deleted bacteriumof claim 24, comprising the following steps: a. providing a sample ofthe gene-deleted bacterium; b. providing a sample of the wide-typebacterium that was used to produce the gene-deleted bacterium; c.performing PCR amplification reactions separately on each thegene-deleted and wildtype samples, using suitable LktCA forward andLktCA reverse primers; and d. determining that the PCR amplicon is ˜2.3kb for the gene-deleted sample and ˜50.0 kb for the wildtype bacterium;thereby confirming the presence of the deletion in the gene-deletedbacterium.
 41. The method of claim 40, wherein the PCR reactions areperformed with primers having the sequence as set forth in SEQ ID NO: 1and
 2. 42. The method of claim 41 further comprising the step ofconfirming that the flanking is origin and kanamycin resistance genesare not present in the gene-deleted bacterium.